(10) Pelvic Diaphragm, Viscera, and Genitalia

The pelvic diaphragm constitutes the muscular floor of the pelvic cavity. Students must identify the following components:

Levator ani mm.: A broad thin muscle group consisting of several parts supporting the pelvic viscera. * Puborectalis m. (puborectal sling): The portion forming a sling around the rectum. * Pubococcygeus m.: The middle part of the levator ani. * Iliococcygeus m.: The most posterior and thinnest part of the levator ani.
Coccygeus m.: The muscle located posterior to the levator ani, completing the pelvic floor.

Identification focuses on the internal and external anatomy of the urinary system within the pelvis.

Trigone: The smooth triangular region of the internal urinary bladder floor.
Ureteric orifices: The openings through which urine enters the bladder from the ureters.
Internal urethral meatus: The opening of the bladder into the urethra.
Internal urethral sphincter: Noted as being a functional, rather than a distinct anatomical, structure in anatomical females.

Prostatic urethra: The segment passing through the prostate (anatomical male).
Membranous (intermediate) urethra: The short segment passing through the deep perineal pouch (anatomical male).
Spongy (penile) urethra: The segment passing through the corpus spongiosum of the penis (anatomical male).
External urethral sphincter: The voluntary muscle controlling urination.
External urethral meatus: The external opening of the urethra.

Internal iliac a. ( $L$ and $R$ ): The primary artery of the pelvis.
Umbilical a.: Often gives off the superior vesical arteries before becoming fibrous. * Superior vesical aa.: Supplies the superior aspect of the bladder. * Medial umbilical ligament: The obliterated distal portion of the umbilical artery.
Obturator a.: Runs along the lateral pelvic wall toward the obturator canal.
Internal pudendal a.: The primary artery of the perineum.
Middle rectal a.: Supplies the middle portion of the rectum.
Inferior rectal a.: (Added via handwritten note) Supplies the lower rectum and anal canal.
Superior gluteal a.: Typically exits the pelvis superior to the piriformis muscle.
Inferior gluteal a.: Typically exits the pelvis inferior to the piriformis muscle.

Sacral plexus ( $L_4 - S_4$ primary ventral rami): The network of nerves supplying the lower limb and pelvic floor.
Lumbosacral trunk ( $L_4$ and $L_5$ primary ventral rami): The nervous contribution from the lumbar plexus to the sacral plexus.
Sciatic n. ( $L_4 - S_3$ primary ventral rami): The largest nerve in the body, exiting through the greater sciatic foramen.
Pudendal n. ( $S_2 - S_4$ primary ventral rami): The primary nerve of the perineum and sensory nerve of the external genitalia.

Testes: The primary male reproductive organs. * Seminiferous tubules: The site of sperm production within the testes.
Epididymis: The coiled tube where sperm is stored and matures.
Ductus deferens: The tube transporting sperm from the epididymis to the ejaculatory duct. * Ampulla of the ductus deferens: The dilated terminal portion of the ductus deferens.
Seminal vesicle: Glands that secrete a significant portion of the fluid that becomes semen.
Ejaculatory duct: Formed by the union of the ductus deferens and the duct of the seminal vesicle.
Prostate gland: A walnut-sized gland that secretes alkaline fluid.

Vagina: The muscular canal leading to the uterus. * Vaginal fornices (s. fornix): The recesses formed between the vaginal wall and the cervix.
Uterus: The primary site of fetal development. * Fundus: The rounded superior portion of the uterus. * Body: The main part of the uterus. * Cervix: The narrow lower neck of the uterus. * Os: The opening of the cervix.

Intrauterine region: The portion of the tube within the uterine wall.
Isthmus: The narrow, medial third of the tube.
Ampulla: The widest and longest part of the tube, where fertilization typically occurs.
Infundibulum: The funnel-shaped lateral end of the tube. * Fimbriated end: The finger-like projections at the end of the infundibulum.

Ovaries: The primary female reproductive organs.
Suspensory ligament of the ovary: Contains the ovarian vessels.
Ovarian ligament: Connects the ovary to the lateral wall of the uterus.
Round ligament of the uterus: Maintains the anteflexion of the uterus during pregnancy.
Vesicouterine pouch: The peritoneal recess between the bladder and the uterus.
Rectouterine pouch: The peritoneal recess between the uterus and the rectum.

The broad ligament is a fold of peritoneum that supports the uterus, ovaries, and uterine tubes. It is subdivided into: